1. Field of the Invention
The present invention relates to a display apparatus, and more particularly to a technology for solving a problem of decrease of luminance of a pixel in an active matrix type display apparatus caused by a voltage drop.
2. Description of the Related Art
Organic electroluminescent displays (hereinafter, also referred to as xe2x80x9corganic EL displaysxe2x80x9d or xe2x80x9corganic EL panelsxe2x80x9d) are attracting attention as new flat-type displays. In particular, active matrix type organic EL displays having thin film transistors (hereinafter, also referred to as xe2x80x9cTFTsxe2x80x9d) as switching elements are regarded as sweeping out the currently prevailing liquid crystal displays in the near future, and are in a fierce development race for practical application.
Unlike liquid crystal displays, organic EL displays have self-luminous devices. This eliminates the need for a backlight which is indispensable to liquid crystal displays, promising apparatuses of yet lower profile and lighter weight. Moreover, organic EL panels are expected for application as a light emitting devices such as the backlight of liquid crystal displays using a self-luminous characteristic.
The organic EL devices are current driven type optical devices which emit light by a current flow, so that the current continues flowing the organic EL device during making the organic EL device emit for display. At this time, the luminance of the organic EL device may sometimes decrease caused by a voltage drop of a power supply line which supplies the current to the organic EL device. In the active matrix type organic EL display apparatus, even if the same luminance data is set to the pixels, the luminance of the pixels sometimes disperse by the influence of the voltage drop, as may degrade the display apparatus.
The present invention has been made in view of the foregoing circumstances and an object thereof is to provide a technology for improving decrease of luminance of a pixel in a display apparatus.
A preferred embodiment according to the present invention relates to a display apparatus. This display apparatus comprises: a plurality of optical elements; a power supply line which supplies electrical energy to each of the optical elements; and a signal line which transmits a control signal to each of the optical elements, wherein a resistance of the power supply line is lower than a resistance of the signal line. Thereby, the decrease or the dispersion of the luminance of the optical elements caused by the voltage drop can be improved.
A cross section of the power supply line may be larger than a cross section of the signal line. Thereby, the resistance of the power supply line can be lowered. A width of the power supply line may be wider than a width of the signal line. A thickness of the power supply line may be thicker than a thickness of the signal line. The cross section of the power supply line can be enlarged without lessening the aperture area of the optical element, by thickening the thickness of the power supply line. A resistivity of a constitutional material of the power supply line may be lower than a resistivity of a constitutional material of the signal line.
The signal line may be a data line which transmits luminance data for controlling each of the optical elements. The signal line may be a scanning line which transmits scan signals for controlling a display timing of each of the optical elements. The data line and the scanning line transmits the voltage signal to each optical element, but the current does not flow through these wires in a steady state, so that the influence of the voltage drop is small. Thus, the aperture area of the optical element can be improved by lessening the cross section of the data line and the scanning line.
It is to be noted that any arbitrary combination or recombination of the above-described structural components and expressions changed between a method, an apparatus, a system and so forth are all effective as and encompassed by the present embodiments.
Moreover, this summary of the invention does not necessarily describe all necessary features, so that the invention may also be sub-combination of these described features.